Electric-arc lamp



(No Model.) 3 Sheets-Sheet 1. H. E. BRADLEY.

ELECTRIC ARC LAMP.

Patented Sept. 11, 1894.

IN VEN 70/? W59,

WITNESSES.

A TTOHNE Y8.

0., wnsummou n c 3 v E L D A R B B H ELECTRIC ARC LAMP.

No. 625,943. Pa ented Sept. 11,1894

W/TNE A TTOHNE VS.

(No Model.) 3 SheetsSheet 3. H. E. BRADLEY.

ELECTRIC ARC LAMP.

A TTOHNE YS,

lNVENTO/a W .552 w Patented Sept. 11, 1894.

m: NORRIS PETERS co, pnmuuma, WASHINGTON, n c

W/TNESSES: fig/5'5 UNITED STATES PATENT OFFIC HAROLD E. BRADLEY, OF NEWBEDFORD, MASSACHUSETTS.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters I'ate nt No. 525,943, datedSeptember 11, 1894:.

Application filed February 28, 1894. 'Serial No. 501,840. (N 0 model.)

To all whom it may concern.-

Be it known that I, HAROLD E. BRADLEY, of New Bedford, in the county ofBristol and State of Massachusetts, have invented a new and ImprovedElectric-Arc Lamp, of which the following is a full, clear, and exactdescription.

My invention relates to improvements in arc lamps, and the object of myinvention is to simplify and cheapen lamps of this class; also toimprove the feed mechanism so that the feed shall be extremely regular,to provide a resistance and cut-out which will work automatically toshort circuit the lamp if the current becomes too strong and so preventthe burning out of the lamp, and in general, to make a lamp which isdurable, easily placed in position, and capable of giving a steadylight.

To these ends, my invention consists of certain features of constructionand combinations of parts, which will be hereinafter described and thenpointed out in the claim.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar figures of reference indicatecorresponding parts in all the views.

Figure 1 is a side elevation, partly in section, of a lamp embodying myinvention. Fig. 2 is a central vertical section on the lines 2-2 ofFigs. 3 and 4. Fig. 3 is a side elevation of the lamp with its inclosingcasing removed. Fig. 4 is a plan view of the same. Fig. 5 is a detailsectional view illustrating the construction of the shunt magnets. Fig.6 is a detail View of a modified form of spool and armature for the mainmagnet. Fig. 7 is a detail view of another modified form of spool andarmature of the main magnet; and Fig. 8 is a diagram of the lampcircuits.

My invention may be used in connection with any ordinary frame andcarbon holder, and as shown, it is provided with abed plate 10,supporting bridges or top plates 11, and posts 12 extending from the bedplate to the top plates, thus forming a frame to which the othermechanism may be secured. The mechanism carried on this frame ispreferably inclosed in a case 13, to protect it from the weather.Extending vertically through the frame is a feed rod 14, which is of theusual kind, and in which the upper carbon of the lamp is held in thecustomary manner. current as it enters the lamp passes through a mainmagnet 15, which is arranged at one side of the feed rod, and preferablyin a horizontal position, the magnet being mounted in suitable supports16, and above it is aswinging armature 17 which is pivoted at one end,as shown at 18, and the movement of the free end of which is limited bya bent arm 18. This armature is provided with a depending arm 19 (seeFig. 1) which is flexibly connected by means of a spring 20, with alever 22 operating the feed mechanism, the spring being adjustablyconnected with the said lever by means of a screw 21 in one end of thelever, and a suitable nut 23 on the screw. By means of this screw andnut, the tension of the spring may be very nicely adjusted.

The lever 22 is arranged in a substantially horizontal position, and isprovided with a rib 22 to give it the necessary strength and lightness,and also to facilitate its connection with other parts. The lever isprovided near the center, at which point it is widened, with a largeperforation 24, through which the feed rod 14 extends, and at oppositesides of the lever are depending ears 25, which are supported on screws26 in the lamp frame, and which thus serve as a fulcrum for the lever.The lever is connected on the side of the feed rod opposite the mainmagnet, with a link 27, which extends downward nearly parallel with thefeed rod, and is at its lower end pivoted to a clutch 28 of the usualkind, which embraces the feed rod and is supported at its opposite endon a screw 29, the point of which rests on the bed plate 10. It willthus be seen that when the current passes through the main magnet, themagnet being energized, draws down the armature 17, which acting on thearm 19 and spring 20, depresses the lever 22, thus lifting the end onthe opposite side of the feed rod, and raising the link 27 and clutch28, which lifts the feed rod and the upper carbon, thus starting thearc.

The main magnet may be so wound that it will have a sufficient amount ofmagnetism to hold its armature and preserve its tension on the springthrough a large change of current quantity. Thus I may make a lamp forcurrents varying from six to ten ampres. Now,if Iwind my main magnet sothat it will The v IOC attract its armature enough to pull it down andstart a current of, say five amperes, it will obviously hold it there aslong as the current is five amperes or more, up to the time when asufficient amount of current should pass to destroy the insulation.After the lamp has picked up, or started to burn, through the action ofthe main magnet, it will continue to burn a constant length of are, eventhough the amperes of current should vary largely, so long as they donot become less than a predetermined value, or great enough to overheatthe magnet.

One end of the lever 22, the end on the side of the lamp opposite themain magnet, is connected by means of a link 30 with the yoke 31 of theplungers 32 of the solenoid shunt magnets 33, this form of magnet beingpreferably employed, although other kinds of magnets may be used ifdesired. The shunt magnets are arranged to operate in connection withthe lever 22 so as to balance in a measure the spring 20 and the pull ofthe main magnet so as to perfectly control the feed, the connection andoperation being fully described below.

The shunt magnets 33 are preferably constructed as shown in Fig. 5, toenable them to be easily placed in or removed from the lamp frame, andas here shown, each magnet is provided with a suitable hollow core 34:,forming the body of the spool, and with heads 35 which are arrangedbetween the bed plate 10 and a cross bar 36 above and parallel with thebed plate, the cores 34 of the spools protruding through the heads 35 soas to enter the bed plate 10 and cross bar 36. The cross bar is held inplace by screws 37 extending from the cross bar to the bed plate, and byremoving the screws and raising the cross bar, the magnets may beremoved or placed in position.

In connection with the feed mechanism, I have provided a cut-out 38 (seeFig. 1) comprising a spring plate 39, which is provided with a shank 40secured to the lamp frame, and a second contact plate ll which issecured to a support 42 above the plate 39, and these plates arenormally separated, but will be drawn together when the voltage of thearc shall exceed a predetermined Value, and so short circuit the lampand prevent it from being burned out. The cut-out is operated by thelever 22, the lower contact plate 39 being connected with the lever 22on the side next the main magnet by means of a rod or screw 39 whichextends downward through the plate 39, with its head below the plate,

and when the lever 22 is tilted by the action of the shunt magnets, to agreat extent, the screw 39 lifts the plate 39 and brings it against theplate 41, thus short circuiting the lamp, as will appear from thedescription of the circuits to be described below.

In connection with the cut-out I have provided a resistance which willbe included in the circuit when the cut-out acts, the object of thisbeing to throw a sufficientamount of current through the main magnet tostart the arc in case the carbons should again come in contact. Theresistance comprises two coils 43, which are secured to the support 4-2and are connected together at the bottom, being fastened to a convenientsupport on the bed plate.

The lamp is provided with the usual binding posts and lamp frame (whichare not shown because they form no part of this invention) and thecurrent comes in through the positive binding post 44:, (see Fig. 8,)passes through the carbons 46, the main magnet 15, and out through thenegative binding post 45. As the arc increases in length, a portion ofthe current passes through the shunt magnets 33, which are connectedwith the carloons as the diagram shows, and the shunt magnets tilt thelever 22 against the tension of the spring 20, thus permitting the feedrod to drop slightly and hold the arc at normal length, the main magnetoperating as already described to lift the feed rod and the shuntmagnets to drop it, and thus the two magnets balance each other andpreserve the length of the are. If the feed rod should descend so far asto materially reduce the dilference of potential existing around theare, then the pull of the shunt magnets on their cores will be decreasedto a su'fficient extent to allow the spring 20 to raise the feed rodthrough the agency of the lever 22, link 27 and clutch 28. The upperplate 4E1 of the cut-outis connected with the positive binding post, andthe lower plate 39 is connected through the resistance coils 3 with thenegative binding post, as the diagram shows. If the end of the lever 22next the shunt magnets is depressed to too great an extent, the lowerplate 39 of the cutout is raised into contact with the plate 41, and thelamp is thus short circuited, the current passing through the cut-outplates and the resistance coils 43, as per diagram, but if the carbonsagain come in contact, the resist ance causes sufficient current to passthrough the main magnet to energize it and again raise the feed rod soas to start the arc.

Instead of constructing the main magnet as shown, it may be made asillustrated in either Fig. 7 or Fig. 6, the magnet in the first casebeing provided with a spool 47, the core of which has a projecting end48 which is concaved on one side, as shown at a9, while opposite thisconcaved end is arranged an armature 50, having a convex side next theconcavity of the core, this arrangement being intended to produce agradual pull on the armature and avoid any abrupt action. The sameeffect is had by arranging the pole pieces of the magnet and thearmature as illustrated in Fig. 6, in which case the spool 51 has itsheads 52 beveled at one edge, as shown at 53, while the armature 54 hasbent ends 55, the incline of which corresponds to the bevel 53, so thatthe action on the armature is thus rendered gradual and positive, a

comparatively large surface of the armature being exposed to magneticaction. The forms of magnets shown in Figs. 6 and 7 may also besubstituted for the solenoids in the shunt circuit, if desired.

In the foregoing description and in the drawings, I have described andshown a feed rod operated by a clutch, but it will be understoodthat ifthe feed rod is provided with a rack, the tilting lever 22 may be gearedto the rack so as to operate substantially as described. A

Having thus described my invention, I claim as new and desire to secureby Letters Patentplate, substantially as and for the purpose set forth.

HAROLD E. BRADLEY.

Witnesses:

BENJ. B. BARNEY, E. L. BARNEY, Jr.

